The present invention relates to a method of manufacturing a surgical model and more particularly, but not exclusively, relates to a method of manufacturing a surgical model which simulates certain aspects of a natural anatomical joint and which is capable of being prepared with realistic simulation of certain pathologies for demonstrating and/or practising appropriate surgical techniques by arthroscopy in a realistic manner using endoscopic surgical instruments.
Surgical models for demonstrating and/or practising surgical techniques by arthroscopy are generally unrealistic. For example, existing models are often anatomically incorrect, at least insofar as the properties of the materials used for the models are concerned, are generally provided with pre-formed portals and are generally not watertight. These shortcomings give rise to significant difficulties in the training of surgeons in arthroscopic techniques in which, for example, the positioning of the portals and irrigation of the joint are particularly important.
It is therefore an object of the present invention to provide a method of manufacturing a surgical model which eliminates or at least reduces these deficiencies of prior art models.
According to the present invention there is provided a method of manufacturing a surgical model simulating certain aspects of the natural anatomical joint, the method comprising the steps of: providing a male mould conforming externally to the general anatomy of an internal cavity of the joint; applying a coating of resilient impermeable penetrable material over the male mould; removing the coating from the male mould to form an open capsule; providing a closure for the capsule and attaching the closure to the open capsule so as to form an impermeable penetrable capsule, the capsule conforming internally to the general anatomy of the internal cavity of the joint and containing simulated joint components; arranging the capsule within a mould, the mould being at least partly lined with a penetrable outer skin material; embedding the capsule in a penetrable packing material; and removing the model from the mould.
The method may include the step of reinforcing the model, for example with a fibrous, mesh or gauze material. The reinforcement may be applied to the coating of resilient material and/or the skin.
The capsule may be filled with fluid such as water or saline, to simulate synovial fluid, which fluid may be pressurised.
The skin of the model and the capsule may be formed of an elastomeric compound such as rubber, for example silicone rubber, or a colloid material, for example based on gelatine.
The packing material may comprise light discrete particulate material such as polystyrene beads or may comprise a moulded light material, for example expanded polystyrene or polyurethane, or may comprise the same material as the skin and/or the capsule.
The closure for the capsule may comprise an articular surface of a bone forming part of the joint.
The method may include the step of passing an elongate member simulating a ligament and/or a tendon through at least a part of the capsule, either before or after the closure is inserted. The elongate member may then be secured externally of the capsule. The elongate member may comprise an elastomeric material. The elongate member may incorporate a flexible elongate element extending from at least one end thereof. The flexible elongate element may extend through the elongate member in the axial direction thereof. The flexible elongate element may comprise string or a like filamentary material.
The joint comprising the surgical model may be in the form of a knee structure, the knee structure comprising femoral condyles with a femoral notch therebetween, medial and lateral menisci, anterior and posterior cruciate ligaments and tibial articular surfaces. The mould for receiving the capsule may be an inverted knee-shape. The method may include the step of arranging within the mould a simulated patellar complex positioned intermediate the capsule and the skin. The patellar complex may incorporate a simulated patella, a simulated patellar tendon and may additionally incorporate a simulated tibial tubercle. The patellar complex may be made of a material harder than the skin and the capsule, for example a harder plastics material such as polyurethane. The patellar complex may allow removal of a part thereof to simulate a bone-tendon-bone graft. The patellar complex may additionally be embedded in the penetrable packing material. The male mould may incorporate recesses conforming to the anatomy of the femoral condyles with the femoral notch therebetween. The male mould may additionally incorporate recesses conforming to one or more of the anatomy of the articular surface of the patella, plicae, the pes anserinus tendon and the fat pad. The coating material may be applied separately to the recesses of the male mould.
The closure for the capsule may comprise an assembly simulating the anatomical features of the medial and lateral menisci, the anterior and posterior cruciate ligaments and the tibial articular surfaces. The assembly may comprise first and second sub-assemblies with the medial and lateral menisci being formed as a first sub-assembly together with the posterior cruciate ligament, and with the tibial articular surfaces being formed as a second sub-assembly together with the anterior cruciate ligament. The sub-assemblies may be interconnected by means of a skirt provided on the first sub-assembly and adapted to extend around the periphery of the second sub-assembly. Additionally, the second sub-assembly may be provided with a recess which receives the posterior cruciate ligament of the first sub-assembly.
The method may include the step of securing the free ends of the posterior and anterior cruciate ligaments within the femoral notch. This may be effected by providing an elongate member extending from the free end of each ligament and by passing the elongate member of one ligament through opposite sides of the femoral notch. The elongate member may then be secured externally of the capsule.
As an alternative, the joint comprising the surgical model may be in the form of a shoulder structure, the shoulder structure comprising a humeral head, an articular surface of the glenoid process, a glenoid labrum and a biceps tendon. The method may include the step of arranging within the mould a simulated scapulo-clavicular complex positioned intermediate at least a part of the capsule and the skin. The scapulo-clavicular complex may incorporate a portion of a simulated clavicle and a portion of a simulated scapula, for example including the acromial and coracoid processes. The scapulo-clavicular complex may be made of a harder material than the skin and the capsule, for example a harder plastics material such as polyurethane.
The male mould may incorporate recesses conforming to the anatomy of the humeral head and the glenoid labrum. The male mould may additionally incorporate recesses conforming to the anatomy of one or more of the lateral end of the clavicle and/or the lateral portion of the acromial process and/or one or more of the claviculo-acromial ligament, the coraco-acromial ligament, the superior and/or middle gleno-humeral ligaments, all or part of the inferior gleno-humeral complex such as one or more of the anterior, axillary and posterior bands, the tendons of the supra spinatus, the infra spinatus and the teres minor muscles may also be formed in the capsule wall, together, optionally, with the sub-scapularis tendon.
The closure for the capsule may simulate the anatomical features of the glenoid process.
The method may include the step of securing a simulated biceps tendon in or externally on opposing walls of the capsule, for example behind the humeral head and above the glenoid labrum.
The capsule may be manufactured as two or more capsule structures. Adjacent capsule structures may be interconnected by means of an aperture.
According to another aspect of the invention there is provided a surgical model in the form of a shoulder structure simulating certain aspects of the natural anatomical joint, the model comprising a penetrable outer skin, an impermeable penetrable capsule within the model, and penetrable packing material around the capsule, wherein the capsule conforms internally to the general anatomy of the internal cavity of the shoulder and contains simulated joint components comprising a humeral head, an articular surface of the glenoid process, a glenoid labrum and a biceps tendon.
The model may be provided with a generally flat base or may be configured to be received in a cradle, which cradle is provided with a generally flat base. The base of the model or the cradle may be formed with at least one recess for engaging with a complementary protrusion formed on a receiving tray.
The model may include a simulated scapulo-clavicular complex intermediate the capsule and the skin. Penetrable packing material may be provided around at least a part of the simulated scapulo-clavicular complex. The scapulo-clavicular complex may incorporate a portion of a simulated clavicle and a portion of a simulated scapula, for example including the acromial and coracoid processes. The scapulo-clavicular complex may be made of a harder material than the skin and the capsule, for example a harder plastics material such as polyurethane.
The components simulating the humeral head and the glenoid labrum may be formed integrally with the capsule, for example they may be formed in the capsule wall.
Components simulating the lateral end of the clavicle and/or the lateral portion of the acromial process may be formed in the capsule wall. Components simulating one or more of the claviculo-acromial ligament, the coraco-acromial ligament, the superior and/or middle gleno-humeral ligaments, all or part of the inferior gleno-humeral complex such as one or more of the anterior, axillary and posterior bands, the tendons of the supra spinatus, the infra spinatus and the teres minor muscles may also be formed in the capsule wall, together, optionally, with the sub-scapularis tendon.
The component simulating the glenoid process may be formed as a separate assembly to the remainder of the capsule. For example, the component may be secured in an aperture formed in the capsule wall.
The biceps tendon may be secured in or externally on opposing walls of the capsule behind the humeral head and above the glenoid labrum.
The capsule may comprise two capsule structures. The capsule structures may be interconnected by means of an aperture which may simulate a tear in the tissue intermediate the two capsule structures.
Various pathologies can be simulated. For example, capsular tears and rotator cuff tears can be formed, such as the aperture intermediate the capsule structures. Alternative tears can allow the surgeon to practise suturing or stapling, or even stapling part of the rotator cuff to a bone in addition to suturing. Other pathologies may be simulated for example by cutting the glenoid labrum to simulate a Bankart lesion.
The capsule may be filled with fluid such as water or saline, to simulate synovial fluid, which fluid may be pressurised, to simulate the conditions under which the appropriate arthroscopic technique would usually be conducted.
The skin of the model and the capsule may be formed of an elastomeric material such as rubber, for example silicone rubber, or a colloid material, for example based on gelatine.
The packing material may comprise light discrete particulate material such as polystyrene beads or may comprise a moulded light material, for example expanded polystyrene or polyurethane, or may comprise the same material as the skin and/or the capsule.
The capsule and/or the skin may incorporate, or may be at least partly surrounded internally of the model by, a reinforcing material, such as a fibrous, mesh or gauze material.
For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which: